Golf ball with a thermoset polyurethane cover

ABSTRACT

A golf ball with an improved cover layer that is formed over the core, and that is a thermoset polyurethane composition or a thermoset polyurea composition, each formed from reactants comprising respective thermoplastic polyurethane or polyurea and a cross-linking hydrolysable organosilane having the general formula: 
     
       
         
         
             
             
         
       
         
         
           
             where, R 1 , R 2 , and R 3  are aliphatic alkyl, aromatic alkyl and n≧1; and 
             R 4  is an organic radical capable of reacting with the polymer backbone moiety, which comprises a cross-linking agent having at least two isocyanate functions. The thermoplastic polyurethane obtained is capable after processing of cross-linking on contact with water molecules to become thermoset. The golf ball can also include an intermediate layer disposed between the core and the cover, where the intermediate layer is composed of a blend of ionomers. The golf ball hydrolysable organosilane cross-linking agent is gamma-methyl aminopropyl methoxy silane.

FIELD OF THE INVENTION

The present invention relates to golf balls and more particularly, theinvention is directed to golf balls with an improved cover layerincluding a thermoset material created from reacting thermoplasticurethane or thermoplastic urea with non-toxic cross-linkableorgano-silanes.

BACKGROUND OF THE INVENTION

Conventional golf balls can be divided into two general types or groups:solid balls or wound balls. The difference in play characteristicsresulting from these different constructions can be quite significant.These balls, however, have primarily two functional components that makethem work. These components are the core and the cover. The primarypurpose of the core is to be the “spring” of the ball or the principalsource of resiliency. The primary purpose of the cover is to protect thecore.

Two-piece solid balls are made with a single-solid core, usually made ofa cross-linked polybutadiene or rubber, which is encased by a hard covermaterial. In these balls, the solid core is the “spring” or source ofresiliency. The resiliency of the core can be increased by increasingthe crosslink density of the core material. As the resiliency increases,however the compression may also increase making a ball with increasedstiffness. Stiffness is a physical attribute defined by load per unit ofdeflection. In the golf ball art, stiffness is commonly measured usingAtti and Rheile “compression” gauges, however, other methods can beused.

Multi-piece solid balls include multi-layer core constructions ormulti-layer cover constructions, and combinations thereof. In a golfball with multi-layer core, the principal source of resiliency is themulti-layer core. In a golf ball with a multi-layer cover, the principalsource of resiliency is the single-layer core.

One conventional material used to form golf ball covers is balata, anatural or synthetic trans-polyisoprene rubber. The softness of thebalata cover allows the player to achieve spin rates sufficient to moreprecisely control ball direction and distance, particularly on shortershots. However, balata covers lack the durability required by theaverage golfer, and are easily damaged. Accordingly, alternative covercompositions have been developed in an attempt to provide balls withspin rates and a feel approaching those of balata covered balls, whilealso providing a golf ball with a higher durability and overall distance

Ionomer resins (e.g., copolymers of olefin, such as ethylene, andethylenically unsaturated carboxylic acids, such as (meth)acrylic acids,wherein the acid groups are partially or fully neutralized by metalions) have also been used as golf ball cover materials. Ionomer coversmay be virtually cut-proof, but in comparison to balata covers, theydisplay inferior spin and feel properties.

Thermoplastic materials are used in golf ball applications, particularlybecause they are easy to implement and have high performance qualitiesat ambient temperature. They are also flexible and have a high degree ofmechanical resistance. Nevertheless, thermoplastic materials have thedrawback of low physical resistance to heat such that the productsobtained from said materials have, depending on their use, a shortservice life. On the other hand, materials known as “thermosetting”materials are difficult to shape, thus even though they may be heatresistant, their use is limited.

Methods have been formulated to form thermoset polyurethane and polyureamaterials for use in golf balls. In order to achieve this, thepreparation of a thermosetting polymer has been proposed by modifyingeasily processed thermoplastic polymers to enable the finished productto be cross-linked. One popular method is the reaction of thermoplasticpolyurethane or polyurea compositions with a toxic isocyanate monomerlike MDI or TDI to create a cross-linking moiety. This is usuallyachieved by achieved by mixing and extruding a polymer, particularly apolyethylene with a peroxide. However, this type of method not only hasthe drawback of being possible with only a limited number ofpolyethylenes, but also of requiring very expensive industrialinstallations.

Other methods include the use of a high energy radiation to produce across-linked TPU, such as irradiating a polymer with doses measuring 80to 200 KGy. It should, however, be noted that this type of treatment isvery expensive and also tends to deteriorate rather than improve thepolymers used.

Hebert, et al., U.S. Pat. No. 5,885,172 (“the '172 patent”) discloses amultilayer golf ball giving a “progressive performance” (i.e. differentperformance characteristics when struck with different clubs atdifferent head speeds and loft angles) and having an outer cover layerformed of a thermoset material with a thickness of less than 0.05 inchesand an inner cover layer formed of a high flexural modulus material. The'172 patent provides that the outer cover is made from polyurethane asdescribed in Wu, et al., U.S. Pat. No. 5,692,974, or thermosetpolyurethanes such as TDI or methylenebis-(4-cyclohexyl isocyanate)(“HMDI”), or a polyol cured with a polyamine (e.g. methylenedianiline(MDA)), or with a trifunctional glycol (e.g.,N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine). The '172 alsoprovides that the inner cover has a Shore D hardness of 65 80, aflexural modulus of at least about 65,000 psi, and a thickness of about0.020 0.045 inches. Exemplary materials for the inner cover areionomers, poly-urethanes, polyetheresters (e.g. HYTREL®),polyetheramides (e.g., PEBAX®), polyesters, dynamically vulcanizedelastomers, functionalized styrene-butadiene elastomer, metallocenepolymer, blends of these materials, nylon oracrylonitrile-butadiene-styrene copolymer.

The problem posed therefore consists in developing a manufacturingprocedure for producing polyurethane that maintains the processingconditions of thermoplastic urethane polymers (TPUs) and preserves theirmechanical characteristics while adding improved heat resistance.

Therefore, a continuing need remains for novel golf ball construction,and particularly for a golf ball cover that has the desirable and/oroptimal combination of performance characteristics, while also havinggood abrasion durability, good hardness, and friction characteristicsthat result in favorable spin.

SUMMARY OF THE INVENTION

The present invention is a more durable polyurethane or polyureamaterial for a golf ball cover. A cover that is formed over the core,and that is a thermoset polyurethane composition or a thermoset polyureacomposition, each formed from reactants comprising respectivethermoplastic polyurethane or polyurea and a cross-linking hydrolysableorganosilane having the general formula:

where, R₁, R₂, and R₃ are aliphatic alkyl, aromatic alkyl and n≧1; and

R₄ is an organic radical capable of reacting with the polymer backbonemoiety, which comprises a cross-linking agent having at least twoisocyanate functions. The thermoplastic polyurethane obtained is capableafter processing of cross-linking on contact with water molecules tobecome thermoset.

The golf ball can also include an intermediate layer disposed betweenthe core and the cover, where the intermediate layer is composed of ablend of ionomers.

In one embodiment of the invention the golf ball hydrolysableorganosilane cross-linking agent is gamma-methyl aminopropyl methoxysilane.

The thermoset golf ball cover has a Shore D hardness ranging from20-70D, preferably 35 to 65D, a flexural modulus of 17 to 80 kpsi,preferably from 25 to 70 kpsi, and a thickness ranging from 0.020 inchto 0.065 inch.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the invention, a method is disclosed for forming agolf ball having a cover or intermediate layer that can be a thermosetpolyurethane or polyurea after processing of a thermoplasticpolyurethane or polyurea. It also relates to the golf ball having athermoset polyurethane or thermoset polyurea cover or inner cover layercreated from the process which is disclosed in U.S. Pat. No. 6,861,491,which is incorporated herein, in its entirety, by reference thereto.Those skilled in the art will recognize that the core may be solid,hollow, multi-piece or liquid-filled, the intermediate layer may bepartitioned into additional layers, and the golf ball may have a woundlayer without departing from the scope and spirit of the presentinvention.

As previously discussed thermoplastic materials are used in making golfballs, particularly because they are easy to implement and have highperformance qualities at ambient temperature, are flexible and have ahigh degree of mechanical resistance. Nevertheless, thermoplasticmaterials have the drawback of low physical resistance to heat such thatthe products obtained from said materials have, depending on their use,a short service life. All standard TPU compositions generally lose theirmechanical characteristics at around 70° C. On the other hand, materialsknown as “thermosetting” materials are difficult to shape, thereforelimiting their use.

The invention incorporates the process of '491 to manufacture golf ballswherein the processing conditions of thermoplastic urethane polymers(TPUs) are maintained while preserving the main mechanicalcharacteristics and adding improved heat resistance that is greater thanthat of cross-linked polyethylenes. By incorporating this process, theuse of toxic isocyanates as cross-linking agents is eliminated, and thelack of abrasion qualities that are inherent with their use.

The method utilized to create the improved thermoset polyurethane (andpolyurea) wherein hydrolysable organosilanes are grafted ontomacromolecular chains of thermoplastic polyurethane that do notdeteriorate the chains. This is achieved by having a cross-linking agentgrafting the hydrolysable organosilane onto thermoplastic polyurethanemacromolecules, with the hydrolysable organosilane having the generalformula:

where, R₁, R₂, and R₃ are aliphatic alkyl, aromatic alkyl and n≧1; and

R₄ is an organic radical capable of reacting with the polymer backbonemoiety, which comprises a cross-linking agent having at least twoisocyanate functions. The thermoplastic polyurethane obtained is capableafter processing of cross-linking on contact with water molecules tobecome thermoset.

In an embodiment R₄ is selected from the group comprising the radicalsNH₂, NH, SH, OH, phenol, epoxy. This list is not limitative and R₄ isunderstood to be any organic radical capable of reacting with anisocyanate function.

Advantageously the cross-linking agent is a diisocyanate with thegeneral formula:

O═C═N—R₅—N═C═O where R₅=organic radical

In selecting both molecules of the organosilane type with R₄=NH₂, NH,SH, OH, phenol, epoxy and molecules of the isocyanate type withfunctionality greater than or equal to 2 made it possible effectively tograft organosilanes to the macromolecular chains of thermoplasticpolyurethane without damaging them. It is to be appreciated that thecross-linking agent can also consist of a triisocyanate function withoutcompromising the scope of the invention.

The method as described has another advantage, viz. the ability to adaptto all types of TPU including esters, ethers, carbonates andcaprolactones. In addition, the selected TPU may be aliphatic oraromatic. Finally, it may be in amorphous or semi-crystalline form. Inan advantageous embodiment of the invention the organosilane isaminopropyltrimethoxysilane, with the formula:

In this situation reactions between thermoplastic polyurethane orthermoplastic polyurea and isocyanate functions cause, eithersimultaneously or with a slight time-lag depending on the mixingprocedure, the formation of aliophanates and isocyanate-amine reactionsaccording to the reaction scheme below:

This series of reactions makes it possible to affix hydrolysable silanegroups onto the polyurethane or polyurea chains without damaging them.The fact of grafting several silanes onto the same thermoplasticpolyurethane or polyurea chain can also encourage subsequentcross-linking.

After processing, the thermoplastic polyurethane (or the thermoplasticpolyurea) cross-links with humidity by hydrolysis and polycondensationof the silane functions grafted onto the various macro-molecular chainsof the TPU in the classic silane hydrolysis and condensation reaction.

The diisocyanate used may advantageously be an aromatic, cycloaliphaticor aliphatic diisocyanate or their dimers.

The diisocyanate selected may advantageously be selected from among thefollowing aromatic diisocyanates: TDI (1-3 diisocyanatomethylbenzene),2,4′-MDI (1 isocyanato-2(4-isocyanatophenyl)methylbenzene), 4,4′MDI(1,1-methylene bis(4-isocyanatobenzene)), 2,4-TDI (2,4diisocyanato-1-methylbenzene) or PPDI (1,4-diisocyanatobenzene) or theirdimers.

The cycloaliphatic diisocyanate selected may advantageously be H₁₂ MDI(1,1-methylene bis(4-isocyanatocyclohexane)). Clearly the above list ofdiisocyanates that can be implemented in the method of the invention isnot exhaustive. The following can be used: HDI (1,6-diisocyanatohexane),CHDI (trans-1,4-diisocyanatocyclohexane), IPDI(5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclo-hexane), TMDI(1,6-diisocyanato-2,2,4 (or 2,4,4)-trimethylhexane), m-TMXDI(1,3-bis(1-isocyanato-1-methylethylbenzene), p-TMXDI(1,4-bis(1-isocyanato-1-methylethylbenzene), NDI(1,5-diisocyanatonaphthalene), polymer MDI (isocyanic acid,polymethylene polyphenylene ester), Desmodur R(1,1′,1″-methyllidynetris(4-isocyanotobenzene)), Desmodur RI(4-isocyanatophenol phosphorothioate (3:1) ester).

The concentration of cross-linking agent required to manufacture thethermoplastic urethane is between 0.1 and 30% by weight of TPU andadvantageously between 3 and 4% by weight. For a concentration lowerthan 1% by weight of TPU, the quantity of cross-linking agent isinsufficient to avoid cutting the primary chains of TPU, resulting inloss of thermo-mechanical properties of the cross-linked polymer.

For a concentration higher than 30% the results obtained are no bettersuch that the method becomes financially less attractive.

At the same time, the concentration of organosilane required to obtainpolyurethane that can be thermoset after processing is between 0.05 and15% of TPU by weight, and advantageously 2%. For a concentration lowerthan 0.5% by weight, the mesh density is insufficient to obtain aninsoluble product. For a concentration higher than 15% by weight theprice of the ingredients becomes financially less attractive.

In a first embodiment a mixture of thermoplastic polyurethane orthermoplastic polyurea are reacted with a cross-linking agent attemperatures between 120° C. to 220° C. to produce a reagentthermoplastic urethane or a thermoplastic urea; the reagentthermoplastic mixture is then brought into contact with an organosilane;and the resulting grafted thermoplastic is then recovered. Thepolyurethane or polyurea compositions that are obtained may subsequentlybe granulated or processed to produce sections of a given shape. Thistype of reaction may be performed in one or two stages in a variety ofreactors such as extruders, calenders, mixing tanks, etc.

When the method of the invention is implemented by extrusion a single-or twin-screw machine is used the profile of which can be easily adaptedto each processed TPU. In this situation the extruder comprises at leasttwo mixing zones and at least three heating zones. The maximumtemperature applied during the extrusion process is between 120° C. and220° C. depending on the type of TPU. This is introduced together withthe molecule comprising at least one isocyanate function; thehydrolysable organosilane is then introduced into the screw machine.

As explained above, the mixture to be extruded is granulated on removalfrom the extruder or immediately processed to obtain sections of a givenshape. In the granular form the method has the advantage of providinghalf-finished products for use in other processes such as extrusion,calendering, injection, etc.

PROPHETIC EXAMPLE

A mixture of TPU marketed by Goodrich under the trade-name Estane 58277together with 2 parts per hundred (phr) of resin of gamma-methylaminopropyl methoxy silane is introduced into the foot of the hopper ofa twin screw extruder at temperatures of 170° C.

The method makes it possible to retain the mechanical characteristics ofthe original polymer at temperatures higher than 40° C.

Of particular note is the simplicity of the method as it requires nofurther stages after processing of thermoplastic polyurethane to obtainthe cross-linking of the finished product.

While various descriptions of the present invention for making athermoset polyurethane or thermoset polyurea golf ball cover orintermediate layer are described above, it is understood that thevarious features of the present invention can be used singly or incombination thereof. For example, the golf ball can include amulti-layer cover. The features of one embodiment can be used with thefeatures of another embodiment. Therefore, this invention is not to belimited to the specifically preferred embodiments depicted therein.

Suitable materials for golf ball core, intermediate and cover layers ofthe present invention include, but are not limited to, polyethylene,including, for example, low density polyethylene, linear low densitypolyethylene, and high density polyethylene; polypropylene;rubber-toughened olefin polymers; copolyether-esters;copolyether-amides; polycarbonates; acid copolymers which do not becomepart of an ionomeric copolymer; plastomers; flexomers; vinyl resins,such as those formed by the copolymerization of vinyl chloride withvinyl acetate, acrylic esters or vinylidene chloride;styrene/butadiene/styrene block copolymers;styrene/ethylene-butylene/styrene block copolymers;acrylonitrile-butadiene-styrene polymers; fluoropolymers; dynamicallyvulcanized elastomers; ethylene vinyl acetates; ethylene methacrylatesand ethylene ethacrylates; ethylene methacrylic acid, ethylene acrylicacid, and propylene acrylic acid; polyvinyl chloride resins; copolymersand homopolymers produced using a metallocene or other single-sitecatalyst; polyamides, amide-ester elastomers, and graft copolymers ofionomer and polyamide, including, for example, Pebax® thermoplasticpolyether block amides, commercially available from Arkema Inc;polyphenylene oxide resins or blends of polyphenylene oxide with highimpact polystyrene, such as NORYL® commercially available by GeneralElectric Company of Pittsfield, Mass.; crosslinked transpolyisopreneblends; polyurethanes; polyureas; polyester-based thermoplasticelastomers, such as Hytrel®, commercially available from E. I. du Pontde Nemours and Company, and LOMOD®, commercially available from GeneralElectric Company; polyurethane-based thermoplastic elastomers, such asElastollan®, commercially available from BASF; natural and syntheticrubbers; partially and fully neutralized ionomers; and combinationsthereof. Suitable golf ball materials and constructions also include,but are not limited to, those disclosed in U.S. Pat. Nos. 6,117,025,6,767,940, and 6,960,630, the entire disclosures of which are herebyincorporated herein by reference.

Particularly preferred materials for outer cover layers of the presentinvention include castable reactive materials, preferably selected fromaliphatic and aromatic thermoset polyurethanes and aliphatic andaromatic thermoset polyureas.

Additionally suitable cover layer materials and methods for forming themare further disclosed, for example, in U.S. Pat. Nos. 5,484,870,6,818,724, and 6,835,794, the entire disclosures of which are herebyincorporated herein by reference.

The golf ball cover layer or at least one sub-layer thereof (e.g., innercover layer, outer cover layer) may have a measure water resistance. Thecompositions may comprise a highly neutralized acid polymer (“HNP”). Asused herein, “highly neutralized” refers to the acid polymer after atleast 70%, preferably at least 80%, more preferably at least 90%, evenmore preferably at least 95%, and even more preferably 100%, of the acidgroups thereof are neutralized. The HNP may be neutralized by a cation,a salt of an organic acid, a suitable base of an organic acid, or anycombination of two or more thereof. Suitable HNPs are salts ofhomopolymers and copolymers of α,β-ethylenically unsaturated mono- ordicarboxylic acids, and combinations thereof. The term “copolymer,” asused herein, includes polymers having two types of monomers, thosehaving three types of monomers, and those having more than three typesof monomers. Preferred acids are (meth) acrylic acid, ethacrylic acid,maleic acid, crotonic acid, fumaric acid, itaconic acid. More preferredacid are (meth) acrylic acid, maleic acid, fumaric acid, and itaconicacid. (Meth) acrylic acid is particularly preferred. As used herein,“(meth) acrylic acid” means methacrylic acid and/or acrylic acid.Likewise, “(meth) acrylate” means methacrylate and/or acrylate.Preferred acid polymers are copolymers of a C₃ to C₈ α,β-ethylenicallyunsaturated mono- or dicarboxylic acid and ethylene or a C₃ to C₆α-olefin, optionally including a softening monomer. Particularlypreferred acid polymers are copolymers of ethylene and an acid selectedfrom (meth) acrylic acid, maleic acid, fumaric acid, and itaconic acid,preferably (meth) acrylic acid. More preferred are copolymers ofethylene and acrylic acid.

The cover layer can have a thickness from 0.020 inch to 0.034 inch,preferably from 0.030 inch to 0.065 inch, more preferably from 0.030inch to 0.050 inch, most preferably from 00.035 to 0.040 inch.Alternatively, the thickness of the cover layer is 0.50 inch or less,preferably 0.05 inch to 0.2 inch, more preferably 0.05 inch to 0.1 inch.The cover layer may have a flexural modulus of 10,000 to 100,000 psi,preferably 15,000 psi to 80,000 psi, more preferably 20,000 to 50,000psi. The Shore D hardness of the cover layer may be 90 or less,preferably 20 to 70, more preferably 30 to 65, and further preferablyfrom 40 to 65.

The core of the golf ball may be solid, fluid-filled, gel-filled, orgas-filled, having a single-piece construction or a multi-piececonstruction that includes a center and one or more outer core layers.Preferred compositions for solid cores include a base rubber (e.g.,polybutadiene rubbers having a 1,4-cis content of at least about 40%), acrosslinking agent (e.g., ethylenically unsaturated acids having 3 to 8carbon atoms and metal salts thereof), an initiator (e.g., peroxides,carbon-carbon initiators, and blends of two or more thereof) and,optionally, one or more additives (e.g., CoR enhancer like halogenatedorganosulfur compounds). The core may be comprised of a polymercontaining an acid group neutralized by an organic acid or a saltthereof, the organic acid or salt thereof being present in an amountsufficient to neutralize the polymer by at least about 80%.

The golf ball core may have a diameter of 0.5 inch or greater,preferably 1 inch or greater, more preferably 1.5 inch or greater, butmost preferably 1.53 inch or greater. The core may have an Atticompression of 20 to 120, preferably 30 to 100, more preferably 40 to90, further preferably 45 to 85, most preferably 50 to 80;alternatively, the compression may be 25 or less, or 20 or less. Thecore may have a CoR of 0.7 or greater, preferably 0.75 or greater, morepreferably 0.77 or greater, further preferably 0.79 or greater, mostpreferably 0.8 or greater. The core may comprise a center and one ormore outer core layers. The outer core layer may have a thickness of 0.5inch or less, preferably 0.3 inch or less, more preferably 0.25 inch to0.3 inch.

One, two, or more optional intermediate layers may be disposed betweenthe core and the cover. The intermediate layer may be part of the coreas an outer core layer, or part of the cover as an inner cover layer. Inone example, an intermediate layer can be formed from a hard, highflexural modulus, resilient material which contributes to the low spin,distance characteristics when they are struck for long shots (e.g.driver or long irons). The material of the intermediate layer can have aShore D hardness of 55-80, preferably 60-75, more preferably 65-72. Theflexural modulus of the intermediate layer can be at least 50,000 psi,preferably from 55,000 psi to 120,000 psi, more preferably from 58,000psi to 100,000 psi. The thickness of the inner cover layer may be from0.020 inches to 0.050 inches, preferably from 0.030 inches to 0.040inches. The intermediate layer preferably has a water vapor transmissionrate (WVTR) lower than that of the cover. More preferably, the WVTR ofthe intermediate layer is no greater than that of an ionomer resin suchas Surlyn®, which is in the range of about 0.45 g/(m²× day) to about0.95 g/(m²× day. The intermediate layer may contain a moisture resistantcomposition by blending a HNP with one or more thermoplastic polymersand elastomers. Examples of thermoplastic polymers suitable for blendingwith a HNP are conventional ionomers such as ionomeric materials soldunder the trade names DuPont® HPF 1000 and DuPont® HPF 2000,commercially available from E.I. DuPont de Nemours and Company.

The resultant golf balls typically have a CoR of about 0.7 or greater,preferably about 0.75 or greater, more preferably about 0.78 or greater,most preferably about 0.8 or greater. The golf balls also typically havean Atti compression of at least about 40, preferably from about 50 to120, and more preferably from about 60 to 100. The golf balls typicallyhave dimple coverage greater than about 60 percent, preferably greaterthan about 65 percent, and more preferably greater than about 75percent. The diameter of the golf ball is preferably from 1.680 inchesto 1.800 inches, more preferably from 1.680 inches to 1.760 inches, mostpreferably from 1.680 inches to 1.740 inches.

In one example, a golf ball cover layer is formed from a thermosetpolyurethane and having a material hardness of Shore D hardness ofbetween 40 and 70. The golf ball has a compression of 90-110. The coverlayer has a thickness of 0.03 inches to 0.05 inches (e.g., 0.033 inches,0.046 inches).

Golf balls of the present invention may have a variety of constructions,typically comprising at least a core and a cover. Optionally, one ormore intermediate layers may be disposed between the core and the cover;the core may be a single solid mass, or include a solid, liquid-filled,gel-filled or gas-filled center and one or more outer core layers; andthe cover may include an outer cover layer and one or more inner coverlayers. Any of the outer core layers, the intermediate layers, or theinner cover layers may be a continuous layer, a discontinuous layer, awound layer, a molded layer, a lattice network layer, a web or net, anadhesion or coupling layer, a barrier layer, a layer of uniformed ornon-uniformed thickness, a layer having a plurality of discrete elementssuch as islands or protrusions, a solid layer, a metallic layer, aliquid-filled layer, a gas-filled layer, or a foamed layer.

As used herein, the terms “araliphatic,” “aryl aliphatic,” or “aromaticaliphatic” all refer to compounds that contain one or more aromaticmoieties and one or more aliphatic moieties, where the reactablefunctional groups such as, without limitation, isocyanate groups, aminegroups, and hydroxyl groups are directly linked to the aliphaticmoieties and not directly bonded to the aromatic moieties. Illustrativeexamples of araliphatic compounds are o-, m-, and p-tetramethylxylenediisocyanate (TMXDI).

The subscript letters such as m, n, x, y, and z used herein within thegeneric structures are understood by one of ordinary skill in the art asthe degree of polymerization (i.e., the number of consecutivelyrepeating units). In the case of molecularly uniformed products, thesenumbers are commonly integers, if not zero. In the case of molecularlynon-uniformed products, these numbers are averaged numbers not limitedto integers, if not zero, and are understood to be the average degree ofpolymerization.

Any numeric references to amounts, unless otherwise specified, are “byweight.” The term “equivalent weight” is a calculated value based on therelative amounts of the various ingredients used in making the specifiedmaterial and is based on the solids of the specified material. Therelative amounts are those that result in the theoretical weight ingrams of the material, like a polymer, produced from the ingredients andgive a theoretical number of the particular functional group that ispresent in the resulting polymer.

The golf balls of the present invention should have a moment of inertia(“MOI”) of less than about 85 and, preferably, less than about 83. TheMOI is typically measured on model number MOI-005-104 Moment of InertiaInstrument manufactured by Inertia Dynamics of Collinsville, Conn. Theinstrument is plugged into a PC for communication via a COMM port and isdriven by MOI Instrument Software version #1.2.

As used herein, the term “polymer” refers to oligomers, adducts,homopolymers, random copolymers, pseudo-copolymers, statisticalcopolymers, alternating copolymers, periodic copolymer, bipolymers,terpolymers, quaterpolymers, other forms of copolymers, substitutedderivatives thereof, and combinations of two or more thereof. Thesepolymers can be linear, branched, block, graft, monodisperse,polydisperse, regular, irregular, tactic, isotactic, syndiotactic,stereoregular, atactic, stereoblock, single-strand, double-strand, star,comb, dendritic, and/or ionomeric.

Other than in the prophetic example, or unless otherwise expresslyspecified, all of the numerical ranges, amounts, values and percentagessuch as those for amounts of materials, times and temperatures ofreaction, ratios of amounts, values for molecular weight (whether numberaverage molecular weight (“M_(n)”) or weight average molecular weight(“M_(w)”), and others in the following portion of the specification maybe read as if prefaced by the word “about” even though the term “about”may not expressly appear with the value, amount or range. Accordingly,unless indicated to the contrary, the numerical parameters set forth inthe following specification and attached claims are approximations thatmay vary depending upon the desired properties sought to be obtained bythe present disclosure. At the very least, and not as an attempt tolimit the application of the doctrine of equivalents to the scope of theclaims, each numerical parameter should at least be construed in lightof the number of reported significant digits and by applying ordinaryrounding techniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the disclosure are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contain certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Furthermore, when numerical ranges ofvarying scope are set forth herein, it is contemplated that anycombination of these values inclusive of the recited values may be used.

As used herein, the term “flexural modulus” or “modulus” refers to theratio of stress to strain within the elastic limit (measured in flexuralmode) of a material, indicates the bending stiffness of the material,and is similar to tensile modulus. Flexural modulus, typically reportedin Pa or psi, is derived in accordance to ASTM D6272-02.

As used herein, the term “water vapor transmission rate” (“WVTR”) refersto the mass of water vapor that diffuses into a material of a giventhickness (e.g., 1 mm) per unit area (e.g., 1 m²) per unit time (e.g.,24 h) at a specific temperature (e.g., 38° C.) and humidity differential(e.g., 90% relative humidity). Standard test methods for WVTR includeASTM E96-00, method E, ASTM D1653-03, and ASTM F1249-01.

As used herein, the term “material hardness” refers to indentationhardness of non-metallic materials in the form of a flat slab or buttonas measured with a durometer. The durometer has a spring-loaded indenterthat applies an indentation load to the slab, thus sensing its hardness.The material hardness can indirectly reflect upon other materialproperties, such as tensile modulus, resilience, plasticity, compressionresistance, and elasticity. Standard tests for material hardness includeASTM D2240-02b. Unless otherwise specified, material hardness reportedherein is in Shore D. Material hardness is distinct from the hardness ofa golf ball portion as measured directly on the golf ball (or otherspherical surface). The difference in value is primarily due to theconstruction, size, thickness, and material composition of the golf ballcomponents (i.e., center, core and/or layers) that underlie the portionof interest. One of ordinary skill in the art would understand that thematerial hardness and the hardness as measured on the ball are notcorrelated or convertible.

As used therein, the term “compression,” also known as “Atticompression” or “PGA compression,” refers to points derived from aCompression Tester (ATTI Engineering Company, Union City, N.J.), a scalewell known in the art for determining relative compression of aspherical object. Atti compression is approximately related to Riehlecompression: Atti compression≈(160−Riehle compression). Compression is aproperty of a material as measured on a golf ball construction (i.e.,on-ball property), not a property of the material per se.

As used herein, the term “coefficient of restitution” or “CoR” for golfballs or subassemblies thereof is defined as the ratio of a ball'srebound velocity to its initial incoming velocity when the ball is firedout of an air cannon into a vertical, stationary, steel plate whichprovides an impact surface weighing about 100 pounds or about 45kilograms. The time periods, T_(in) and T_(out), of the ball flightbetween two separate ballistic light screens placed between the aircannon and the plate are measured to calculate CoR=T_(out)/T_(in). Thefaster a golf ball rebounds, the higher the CoR it has, the more thetotal energy it retains when struck with a club, and the longer the ballflies. The reported CoR's initial velocity is about 50 ft/s to about 200ft/s, and is usually understood to be 125 ft/s, unless otherwisespecified. A golf ball may have different CoR values at differentinitial velocities.

Another CoR measuring method uses a launching device, a circulartitanium disk of 200 g and 4-inch in diameter to simulate a golf club,and two separate ballistic light screens placed there between. Theimpact face of the disk may also be flexible and has its own CoR. Fromthe two time periods, disk mass (M_(e)), and ball mass (M_(b)), CoR canbe calculated as follows:

${CoR} = \frac{{\left( {T_{out}/T_{in}} \right) \times \left( {M_{e} + M_{b}} \right)} + M_{b}}{M_{e}}$

A “Mooney” viscosity is a unit used to measure the plasticity of raw orunvulcanized rubber. The plasticity in a Mooney unit is equal to thetorque, measured on an arbitrary scale, on a disk in a vessel thatcontains rubber at a temperature of 100° C. and rotates at tworevolutions per minute. The measurement of Mooney viscosity is definedaccording to ASTM D-1646.

As used herein and to conventional practice, the unit “phr” refers to“parts by weight of a respective material per 100 parts by weight of thebase polymer or polymer blend.”

All patents and patent applications cited in the foregoing text areexpressly incorporated herein by reference in their entirety.

The invention described and claimed herein is not to be limited in scopeby the specific embodiments herein disclosed, since these embodimentsare intended solely as illustrations of several aspects of theinvention. Any equivalent embodiments and various modifications apparentto those skilled in the art are intended to be within the scope of thisinvention. It is further understood that the various features of thepresent invention can be used singly or in combination thereof. Suchmodifications and combinations are also intended to fall within thescope of the appended claims.

1. A golf ball comprising: a core; and a cover formed over the core, thecover composed of a thermoset polyurethane material formed fromreactants comprising a thermoplastic polyurethane, a cross-linking agentcomprising at least two isocyanate groups, and a hydrolysableorganosilane having the general formula;

where, R₁, R₂, and R₃ are aliphatic alkyl, aromatic alkyl and n≧1 and R₄is an organic radical capable of reacting with the polymer backbonemoiety, which comprises a cross-linking agent having at least twoisocyanate functions. The thermoplastic polyurethane obtained is capableafter processing of cross-linking on contact with water molecules tobecome thermoset.
 2. The golf ball according to claim 1 furthercomprising at least one intermediate layer disposed between the core andthe cover.
 3. The golf ball according to claim 2 wherein theintermediate layer has a thickness between 0.020 to 0.050 inch.
 4. Thegolf ball according to claim 2, wherein the intermediate layer iscomposed of a blend of ionomers that include cross-linking polyurethaneand polyurea.
 5. The golf ball according to claim 1, wherein thehydrolysable organosilane is gamma-methyl aminopropyl methoxy silane. 6.The golf ball according to claim 1, wherein the thermoset polyurethanecomposition has a Shore D hardness of 20-70.
 7. The golf ball accordingto claim 1, wherein the thermoset polyurethane composition has aflexural modulus of 17,000 to 80,000 psi.
 8. The golf ball according toclaim 1 wherein the cover has a thickness ranging from 0.030 inch to0.065 inch.
 9. A golf ball comprising: a core; and a cover formed overthe core, the cover composed of a thermoset polyurea material formedfrom reactants comprising a thermoplastic polyurea, across-linking agentcomprising of at least two isocyanate groups, and a hydrolysableorganosilane having the general formula;

where, R₁, R₂, and R₃ are aliphatic alkyl, aromatic alkyl and n≧1; andR₄ is an organic radical capable of reacting with the polymer backbonemoiety, which comprises a cross-linking agent having at least twoisocyanate functions. The thermoplastic polyurethane obtained is capableafter processing of cross-linking on contact with water molecules tobecome thermoset.
 10. The golf ball according to claim 9 furthercomprising at least one intermediate layer disposed between the core andthe cover.
 11. The golf ball according to claim 10 wherein theintermediate layer is composed of a blend of ionomers.
 12. The golf ballaccording to claim 9, wherein the hydrolysable organosilane isgamma-methyl aminopropyl methoxy silane.
 13. The golf ball according toclaim 9, wherein the thermoset polyurea composition has a Shore Dhardness of 20-70.
 14. The golf ball according to claim 9, wherein thethermoset polyurea composition has a flexural modulus of 15,000 to80,000 psi.
 15. The golf ball according to claim 9 wherein the cover hasa thickness ranging from 0.030 inch to 0.065 inch.
 16. A golf ballcomprising: a core comprising a polybutadiene mixture, the core having adiameter ranging from 1.35 inches to 1.64 inches and having a PGAcompression ranging from 50 to 90; an intermediate layer formed over thecore, the intermediate layer composed of a blend of ionomer materials,the intermediate layer having a thickness ranging from 0.020 inch to0.075 inch, the blend of ionomer materials having a Shore D hardnessranging from 50 to 75 as measured according to ASTM-D2240; and a coverformed over the intermediate layer, the cover composed of athermosetting polyurethane material formed from reactants comprising athermoplastic polyurethane and a hydrolysable organosilane, wherein thethermosetting polyurethane material has a Shore D hardness ranging from30 to 60 as measured according to ASTM-D2240, and a thickness rangingfrom 0.020 inch to 0.030 inch.